install_target creates the install target. The files target is a prerequisite of the install target and if make_rules(3) is also called, the commands of the files target will be executed when subdirs has been recursed.
If kernel(3) is called after install_target has been called, a prerequisite will be added to the install target to install kernel modules that has been built by the kernel target.
If kernel(3) is called before install_target, no kernel modules in the kernel source tree will be installed by the install target.